Re: [sdcc-devel] [ sdcc-Feature Requests-3565759 ] More efficient initialization

[Philipp K. K. <pk...@sp...>]

On 01.10.2012 06:26, Maarten Brock wrote:
>>> IMHO char *p = (char *)0 and char *p = NULL are not the same thing (at
>>> least theoretically): in the first case p is a pointer to a value on
>>> address 0 while in the second case is a pointer to an undefined address,
>>> in sense of "nil" or "null" pointers or references in other languages.
> 
> IMO they are different too. 0 is an integer and NULL is a pointer.
> Otherwise you might as well use 0.0f or 'false' to initialize a pointer.

"An integer constant expression with the value 0, or such an expression
cast to type void *, is called a null pointer constant.66) If a null
pointer constant is converted to a pointer type, the resulting pointer,
called a null pointer, is guaranteed to compare unequal to a pointer to
any object or function." (C11, 6.3.2.3)

> 
>> Well, either way using 0 will yield the desired result, since the
>> implementation will cast it to whatever null pointer constant it prefers.
> 
> Hmmm, I can make the same statement about using NULL.
> 
>>> In short: IMHO it is better to use NULL instead of 0, (void *)0 or (char
>>> *)0. (At least until somebody convinces me that I'm wrong ;-) ).
>>
>> Well, 0 vs. NULL is just a stylistic matter. Personally, I prefer 0, but
>> the C community seems to be divided on this issue.
> 
> I prefer to use an integer value to initialize an integer variable and to
> use a pointer value to initialize a pointer variable. And especially in a
> structure as big as PORT you can use all the help you can get.

0 is just as much a pointer as is NULL, NULL might just be defined as 0.
The port structure is quite huge. If Visual C supported it one might wnt
to use designated initializers there to state intentions more clearly.
But since there's already a lot of NULL in the structure, I don't really
object to make the 0 I used into NULL there for now.

Philipp